1. Field of the Invention
This invention relates to a bicycle stem with an adjustable tilt. At one of its ends, the stem carries the handlebar of the bicycle, and at its opposite end, it is attached to the upper portion of the pivoting tube that is mounted to rotate in the steering socket of the bicycle frame.
2. Description of the Related Art
The advantage of the adjustable tilt of the stem resides in the fact that it can be adapted to be convenient to individuals assuming a different position on the bicycle.
So as to be able to adjust the tilt of the stem, the means of attaching the stem to the pivoting tube comprise articulation means as is known from, for example, the publications CN200992282, U.S. Pat. Nos. 5,327,798 or 5,842,385.
A bicycle stem with an adjustable tilt in which two cylindrical tightening elements are used that extend axially inside a hole for receiving a pivoting tube at the end of the stem is also known from the publication US 2009/079160. These two tightening elements are provided with a respective convex hemisphere cooperating with a corresponding recess that is provided in a housing so as to form an articulation that makes it possible to adjust the tilt of the stem. However, this configuration is extremely complicated to implement, all the more so since the adjustment of the tilt is difficult to carry out due to the tightening of a screw that compresses the headset, thus creating significant friction between the hemispheres and the recesses of the stem. It will therefore be necessary to loosen the headset to adjust the tilt of the stem. Another drawback of this stem is that it does not allow the presence of streaks or serrations on the contact surfaces, which otherwise would allow better holding of the elements and an adjustment by indexing.
Thus, all of the known stems of this type are relatively complicated by their design and comprise a large number of parts to assemble, which leads to a heavy weight and a high cost and often also a loss of rigidity of the unit.
So as to implement an adjustment of the length of the stem to prevent, to a certain extent, producing a range of stems of different lengths, U.S. Pat. No. 5,842,385 also proposes housing the handlebar in an insert with an eccentric hole. However, the adjustment is relatively complicated to carry out since by rotating the insert, the angle of inclination of the stem is also modified.
Furthermore, the selection of the height of the conventional stems is carried out by cutting the pivoting tube to the desired length, and annular inserts are then placed between the stem and the steering tube. This height is thus adjustable by varying the number of inserts.